A transport device of the above kind for successive reduction of the pressure by repeatedly changing a gas/particle stream is disclosed in European Patent 0 108 505 applied to a PFBC power plant. In this a combustor and a cleaner for combustion gases are enclosed within a pressure vessel and surrounded by compressed combustion air. The operating pressure in the plant may amount to about 20 bar. In its most appropriate embodiment the transport device comprises a number of parallel tubes which are connected in series with a number of transfer chambers where the diversion of the gas/particle stream occurs. A special embodiment of a transfer chamber is shown and described in Swedish patent application 8500923-1. The pressure-reducing transport device may be designed and arranged as a cooler for separated dust from the combustion gases in the PFBC power plant.
A transport device designed as an ash cooler and provided with transfer chambers according to the invention is shown and described in the Swedish parallel application 8900133-3.
The material to be fed out from a gas cleaner or a combustor is often abrasive and has a high temperature, up to about 900.degree. C. Since the transport device is able to operate continuously and without valves, as in lock hopper systems, it is exceedingly suitable for feeding out dust/ashes from gas cleaners.